Circuit breaker with improved trip means



Dec. 1, 1970 E. w. KUHN CIRCUIT BREAKER WITH IMPROVED TRIP MEANSy medoct. 24, 1968 5 SheQts-Shcet 1 l INVENTOR Edmund W. Kuhn WITNESSESflaQ/M MJ@ ATTORNEY Dec. 1, 1970 E. w. KUHN 3,544,932

CIRCUIT BREAKER WITH IMPROVED TRIP MEANS Filed 0611.24, 1968 5Sheets-Sheet 2 FIGA. |99

FIG2.

Dec. 1, 1970 l E. w. K U HN 3,544,932

CIRCUIT BREAKER WITH IMPROVED TRIP MEANS Filed OCl.. 24, 1968Sheets-Sheet 5 United States Patent O 3,544,932. CIRCUIT BREAKER WITHIMPROVED TRIP MEANS Edmund W. Kuhn, Pittsburgh, Pa., assignor toWesting- House Electric Corporation, Pittsburgh, Pa., a corporation ofPennsylvania Filed Oct. 24, 1968, Ser. No. 770,305 Int. Cl. H01h 9/20U.S. Cl. 335-174 9 Claims ABSTRACT F THE DISCLOSURE A circuit breakerhaving improved trip means. The trips means is a magnetic trip devicehaving magnetic pole-piece means, a magnetic fixed keeper, a moveablekeeper having an actuator connected to the moveable keeper to trip thebreaker upon the occurrence of abnormal or over load current conditions.

BACKGROUND AND OBJECTS OF THE INVENTION For certain applications ofcircuit breakers, it is desirable to provide a flux-transfer trip deviceof the type comprising a plurality of magnetic circuits with means fortransferring magnetic ux from a first circuit to a second circuit toeffect release of a movable keeper in the rst circuit to thereby effecta tripping operation of the circuit breaker. An object of this inventionis to provide an improved circuit breaker comprising a flux-transfertrip device with a movable keeper positioned at one end of the tripdevice and an actuator operatively connected to the movable keeper andextending to the other end of the trip device to actuate the operatingmechanism of the circuit breaker in order to effect an opening operationof the circuit breaker upon the occurrence of certain over load currentconditions.

Another object of this invention is to provide an irnproved circuitbreaker comprising a flux-transfer trip device having a movable keepermovable to a tripping position to effect a tripping operation of thecircuit breaker and resilient reset means operated by a rigid part ofthe circuit breaker operating mechanism to reset the movable keeperwithout applying damaging forces to the parts of the trip device.

A further object of this invention is to provide a circuit breaker withan improved flux-transfer trip device comprising a movable keeper and anactautor connected to the movable keeper with shock-absorbing means forpermitting movement of the actuator relative to the movable keeper undershock conditions.

A more general object of this invention is to provide a circuit breakerwith an improved flux-transfer trip device that is reliable in operationand relatively easy to manufacture and to assemble into operatingrelationship With parts of the circuit breaker.

SUMMARY OF THE INVENTION An improved circuit breaker comprises aflux-transfer type trip device that may be pulsed by a low energyelectrical signal supplied under abnormal or overload conditions inorder to effect a tripping operation of the circuit breaker. The tripdevice comprises a pair of spaced pole pieces with a movable keeperpositioned at one end of the pole pieces and a xed keeper positioned atthe other end of the pole pieces. A permanent magnet structure ispositioned between the pole pieces and between the tixed and movablekeepers in order to supply magnetic flux. The magnetic device isconstructed with a gap between the fixed keeper and the pole pieces. Themovable keeper, in the set position thereof, engages the pole pieces.With the Lice movable keeper in the set position, most of the magneticiiux from the permanent magnet structure operates through a magneticcircuit, that comprises the movable keeper, to work to maintain themovable keeper in the set position. The remainder of the magnetic fluxpasses through another magnetic circuit that includes the fixed keeper.An actuator, that is operatively connected to the movable keeper at oneend thereof, extends through opening means in he trip device and isoperatively connected, at the other end thereof, to a trip member.Spring means biases the movable keeper and actuator toward a trippingposition. A pair of coils are conneced in series and to the magneticdevice in order to buck the magnetic ux through the one magnetic circuitto raise the reluctance of the one magnetic circuit when the coils arepulsed to thereby effect a transfer of magnetic flux from the onemagnetic circuit to the other magnetic circuit in order to effectrelease of the movable keeper. Upon release of the movable keeper, thespring means biases the movable keeper and actautor to a trippingposition to operate the trip member to effect a tripping operation ofthe circuit breaker. The movable keeper is operatively connected to theactuator through a shock-absorbing spring so that under shock conditionsthe actuator can move slightly relative to the movable keeper Withoutthe full force of the shock of the actautor being transmitted to themovable keeper. Resilient reset means, which is operatively connected tothe actuator, is engaged by a rigid part of the circuit breakeroperating mechanism in order to reset the movable keeper and actuatorduring an opening operation of the circuit breaker. With the provisionof resilient reset means the construction and positioning of parts isless critical and a rigid part of the operating mechanism can operate toreset the actuator and movable Ikeeper without applying damaging forcesto the parts of the trip device. The magnetic device is mounted withinan enclosure, and the actuator extends out through an opening in theenclosure Where the trip member and resilient reset means areoperatively connected to the trip device.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. y1 is a side elevational view,partly in section and with parts broken away, of a three-pole circuitbreaker embodying principles of this invention;

FIG. 2 is a sectional View, with parts broken away, taken generallyalong the line II-II of FIG. 1;

FIG. 3 is a sectional view taken generally along the line lIII-III ofFIG. 2;

FIG. 4 is a view similar to FIG. 3 with the trip device operated to thetripping position and With the circuit breaker tie bar still in theclosed position;

FIG. 5 is a view similar to FIG. 4 with the circuit breaker tie bar inthe open position and the trip device operated to the reset position;

FIG. 6 is a side sectional view of the trip device seen in FIGS. 3-5with the reset member and trip member shown in full lines in theposition illustrated in FIG. 5 and with the reset member shown in brokenlines in the position illustrated in FIG. 3;

FIG. 7 is a view similar to FIG. 6 with the trip device shown in thetripping position illustrated in FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, thereis shown, in FIG. 1, fa circuit breaker 5 comprising a metallicsupporting frame structure indicated generally at 7 and acircuit-breaker structure indicated generally at 9 supported on thesupporting frame structure 7. Except for the trip device that will behereinafter more specifically described the circuit breaker 5 isidentical to the circuit breaker described in 3 the patent to G. D.Gamel et al. Pat. No. 3,045,083, issued July 17, 1962. Thus, only abrief description of the circuit breaker will be provided herein.

The circuit breaker 5 is a three-pole circuit breaker with each polecomprising a stationary contact structure 11 and a movable contactstructure 13. Each of the movable contact structures 13 is supported ona contact arm 15 that is supported for movement about a xed pivot 17. Acommon elongated rigid tie bar 19 extends across the three-pole units.In each pole unit a separate insulating connector 21 is connected to thetie bar 19 and to the associated contact arm to connect the threecontact arms 15 for simultaneous movement upon movement of the tie bar19. The tie bar 19 is operated between open and closed positions byoperation of an operating mechanism indicated generally at 23.

The operating mechanism 23 comprises an operating lever 25 supported ona pivot pin 27 that is supported'on the supporting structure 7. Thelever 25 is pivotally connected to the tie bar 19 to operate the tie bar19. An operating linkage, comprising toggle links 29, 31 and 33, isprovided to hold the lever 25 in the closed position and to operate thelever 25 between the open and closed positions. The toggle link 29 ispivotally connected to the lever 25 by means of a pivot pin 35. The link31 is connected to the link 29 by means of a knee pivot pin 37 andpivotally connected to the link 33 by means of a knee pivot pin 39. Thelink 33 is supported for pivotal movement on a fixed pivot pin 41 thatis mounted on the supporting structure 17.

The linkage 29, 31, 33 comprises two toggles one of which 29, 31functions as a tripping toggle and the other of which 31, 33 functionsas a closing toggle. The tripping toggle 29, 31 is normally slightlyunderset above a line drawn through the pivot pins 39, 35, and theclosing toggle 31, 33 is normally slightly underset below a line drawnthrough the pivots 37, 41.

The tripping toggle 29, 31 is normally biased in a direction to causeits collapse by springs 43, that are positioned in each pole unitbetween the support structure 17 and movable contact arm 15, which biasthe contact arms 15 in an opening direction and bias the connectingmembers 21 toward the left. The tripping toggle 29, 31 is normallyprevented from collapsing by means of a main latch member 45 that ispivoted on a pin 47 and connected by a link 49 to the knee pivot 37 ofthe toggle 29, 31. The link 49 is pivotally connected to the latch 45 bymeans of a pivot pin 51.

The main latch 45 is held in latching position by an intermediate latchlever 53 that is pivoted on a pin 55 that is supported on the supportingstructure 17. The latch 53 carries a latch roller 57 which normallyengages the main latch 45 to releasably hold the main latch in thelatching position seen in FIG. 1. The latch lever 53, at its lower end,carries a latch portion 59 that normally engages a latch roller 61 on alatch member 63 that is supported for pivotal movement on a pin 65 thatis supported on the support structure 7. The latches 53 and 63 arebiased by spring means (not shown) to the latching positions seen inFIG. 1.

As long as the main latch 4S is held in latching position by thelatching mechanism just described, the tripping toggle 29, 31 will,through the link 49, be held in the closed position. The closing toggle31, 33 is normally prevented from collapsing by a shouldered supportmember 69 pivoted on the pin 55 and biased by a spring 71 intosupporting engagement with the knee pin 39 of the toggle 31, 33.

The circuit breaker is shown in FIG. l in the closed and latchedposition with the support member 69 supporting the closing toggle 31, 33in its extended thrust transmitting position. The circuit breaker isautomatically tripped open by operation of a trip device 75 indicated bybroken lines in FIG. 1 and shown in FIGS. 2 7. The trip device 75, whichoperates against a part 77, that is 4 ixedly secured to the latch 63,will be hereinafter more speciiically described.

Upon the occurrence of an abnormal or overload condition above apredetermined value in any of the pole units, the trip device isoperated to operate against the part 77 of the latch 63 to pivot thelatch 63 counterclockwise (FIG. 1) to thereby disengage the latch roller61 from the latch portion 59 of the latch lever 53. The latchingengagement of the main latch 45 with the latch roller 57 is of theslip-oit type, and as soon as the latch lever 53 is released it is movedto an unlatching position by the upward force applied to the main latch45 through the link 49. The tripping toggle 29, 31 immediately collapsespermitting counterclockwise movement of the operating lever 25 andopening movement of the tie rod 19 with the tie rod 19 moving from theposition seen in FIG. 1 to the position seen in FIG. 5 during whichmovement the contact arms 15, which are operatively connected to the tiebar 19 by means of the connectors 21, pivot about the pivots 17 from theclosed position seen in FIG. 1 to an open position wherein the movablecontacts 13 are disengaged from the stationary contacts 11. During thecollapse of the tripping toggle 29, 31, a portion of the toggle link 31engages and actuates the support member 69 against the bias of thespring 71 to a non-suporting position thereby freeing the closing toggle31, 33. The closing toggle thereupon collapses dovmward- 1y to reset andrelatch the tripping toggle 29, 31.

The linkages 29, 31 and 31, 33 are trip free. During an openingoperation, the contacts cannot be closed until the closing togglecollapses resetting the linkages for a closing operation.

The opening operation can also be initiated manually by a trip lever(not shown) that also rotates the latch 63 to the unlatching position.

A spring closing mechanism indicated generally at 79 is provided formanually closing the breaker. The spring closing mechanism 79 ispartially enclosed within a U- shaped housing S1 that is xedly securedto the support structure 7. The spring closing mechanism 79 comprises aclosing spring 83 that is supported between a top spring support 85 anda bottom spring support 87, which spring supports are supported forrectilinear movement within the housing 81. A guide bolt 89 is connectedto the bottom spring support 87 to move with the bottom spring support87, and a guide bolt 91 is connected to the top spring support 85 tomove with the top spring support 85. A toggle link 93 is pivotallyconnected to a cross bolt 95 that is connected to the top springsupport, and a toggle link 97, that is pivotally connected to astationary cross bolt 99, is pivotally connected to the toggle link 93.The bottom spring support 87 is connected to a cross bolt 101 that moveswith the bottom spring support 87. The toggle link 97 is also pivotallyconnected to a vertically movable thrust rod 105. The thrust rod has anopening in its upper end for receiving the pin 39.

A lift link 109 is provided for lifting the bottom spring support 87.The lift link 109 is a at member that passes through an opening in thetop spring support 85 and has an angle shaped lower portion 111projecting through an opening in the bottom spring support 87. The crossbolt 101 passes through an opening in the portion 111 of the lift link109 so that upward movement of the lift link 109 will lift the bottomspring support 87.

A handle structure indicated generally at 113 is provided to operate anoperating shaft 115 (FIG. 2). The handle structure 113 is morespecifically described in the above-mentioned application of G. D. Gamelet al. U.S. Pat. No. 3,045,083. The shaft 115 (FIG. 2) is supported formovement about a fixed axis. A plate 117, which is xedly secured to theshaft 115, is pivotally connected to the upper end of the lift link 109by means of a pin 119.

The parts of the circuit breaker are shown in FIG. 2 in the openposition. In order to close the breaker, the handle structure 113(FIG. 1) is rotated to rotate the shaft 11S (FIG. 2) clockwise. As theplate 117 (FIG. 2) rotates clockwise, the link 109 is lifted to lift thebottom spring support 87. Upward movement of the top spring support 85is prevented because the links 93, 97 are on dead center. The upwardmovement of the link 109, therefore, lifts the bottom spring support 87to compress the spring 83 between the spring supports 87, 85. As thelink 109 moves upward (FIG. 2) a roller 123|, that is connected to thepin 119, operates against the toggle link 33 (FIG. 1), which toggle link33 is collapsed when the breaker is in the open position of FIG. 2, topivot the toggle link 33 counterclockwise about the pivot 41 raising thethrust rod 105 which rotates the toggle link 97 to move the toggle 93,97 olf of dead center permitting the toggle 93, 97 to collapse tothereby permit upward movement of the top spring support 85 under theforce of the charged spring 83 which has been charged by the upwardmovement of the lower spring support 87. The Spring 83 then expandsrapidly moving the top Spring support 85 upwardly to force the thrustrod 105 upward. Upward movement of the thrust rod 105 from the openposition to the closed position operates, with the tripping toggle 29,31 in the thrust-transmitting position, to move the closing toggle 31,33 to the closed position seen in FIG. 1 during which movement the lever2'5 is pivoted clockwise about the pivot 27 to move the tie bar 19 fromthe open position seen in FIG. to the closed position seen in FIG. 1.Movement of the tie bar 19 to the closed position operates through theconnectors 21 to pivot the three contact arms 115, about the pivots 17,to the contactclosed position seen in FIG. l.

The trip device 75 (FIGS. 6 and 7) comprises a trip housing structure127 and a magnetic device 129 supported within the housing 127. Themagnetic device 129 comprises a pair of magnetic steel pole pieces 131,133, a conducting coil 135 around the pole piece 131, a conducting coil137 around the pole piece 133 and four permanent magnet members 139,141, 142, 143, which members 139, 131, 135, 137, 139, 141, 142 and 143are all potted in an insulating epoxy resin 145 which encapsulates thesemembers and supports them as a unitary structure. The permanent magnetmembers 139, 141, 142, 143 form a permanent magnet structure indicatedgenerally at 149 which is formed of the four members merely tofacilitate assembly using readily available magnet members. Thepermanent magnet structure 149 is a rubber bonded barium ferritepermanent magnet material that is available under the trade namePlastiform As can be understood with reference to FIG. 6, an opening 151is drilled through the permanent magnet structure 149 and insulatingcasing 145. A magnetic steel fixed keeper 153 is iixedly secured to oneend of the pole pieces 131, 133 with an insulating sheet 155 sandwichedbetween the fixed keeper 153 and pole pieces 131, 133 to provide a gapbetween the xed keeper 153 and the pole pieces 131, 133. As can beunderstood with reference to FIG. 6, the opening 151 extends through theinsulating plate 155 and the lixed keeper 153. The xed keeper 153 issecured to the pole pieces 131 by a pair of nuts 157 that are threadedonto bolts 159 that are embedded in the epoxy 145 when the epoxy 145 ispotted. An actuating rod 161 extends through the opening 151. As can beunderstood with reference to FIG. 6, the opening 151 is drilled suchthat there is a small-diameter portion 163 of the epoxy resin whichreceives the rod 161 to guide the rod for rectilinear back-and-fourthmovement in the opening 151. The actuating rod 151 extends through anopening in a magnetic steel movable keeper 165. A washer 167 is providedon the outer end of the rod 161, and a nut 169 is threaded on the rod161 against the washer 167 so that as the rod 161 is moved to the right(FIG. 6) this movement will pull the movable keeper 165 to the right tothe set position seen in FIG. 6 wherein the movable keeper 165 engagesthe pole pieces 131, 133. A shock-absorbing coil spring 171 is supportedbetween a spring support 173 that engages a shoulder portion of the 75rod 161 and a spring support 175 that engages the movable keeper 165. Acoil spring 179 is supported between a spring support 181 that engages ashoulder of the actuating rod 161 and a spring support 183 that engagesthe housing 127 to actuate the actuating rod 161 to the left (FIG. 6)upon release of the movable keeper 165.

The trip device also comprises a supporting bracket 185 that is fixed tothe one end of the housing 127, a trip member 187 that is pivotallysupported on a pin 189 that is supported on the 'bracket 185 and a resetmember 191 that is pivotally supported on a pin 193 that is supported onthe bracket 185. The trip member 187 is a generally U-shaped member withthe pin 189 passing through the opposite legs thereof. The bight portionof the trip member 187 is extended outward to provide an actuatingextension 195. The reset member 191 is a resilient reset membercomprising a rigid generally U-shaped member 197 and a resilientleaf-spring 199 secured to the member 197. The pin 193 extends throughthe legs of the U-shaped member 197. A tension spring 201 is connectedto a bentover portion of the member 197 at one end thereof and to abent-over portion of the supporting bracket 185 at the other end thereofto bias the reset member 191 in a clockwise (FIG. 6) direction. Themember 197 is provided with an extension 203 that engages the bightportion of the trip member 187 between the legs of the trip member 187in a manner to be hereinafter described. The trip member 187 ispivotally connected to the actuating rod 161 by means of a loose-ttingpin 207.

The trip device 75 is shown in FIG. 6 in the set position with theleaf-spring member 199 shown in broken lines in the position that themember 199 would assume under the bias of the spring 20-1 when the tiebar 19 is in the contactclosed position shown in broken lines. The tripdevice 75 and parts 19, 77 are shown in FIG. 3 in the set position withthe tie bar 19 shown in the contact-closed position and the part 77 ofthe latch `63 shown in the latching position. As can be understood withreference to FIG. 6, the permanent magnet structure 149 generatesmagnetic flux which passes through the magnet structure 149, the polepiece 133, the movable keeper 165, the pole piece 131 and back throughthe magnet structure 149. IPart of the flux generated in the magnetstructure 149 passes through the magnet structure 149, the pole piece133, the gap 155, the fixed keeper 153, the gap 155, the pole piece 131back through the magnet structure 149. Thus, there are two magneticcircuits in the magnetic device 129 with the greater portion of themagnetic flux from the magnet structure 149 passing through the onemagnetic circuit which includes the movable keeper 165 and with theremainder of magnetic iiux passing through the higherreluctance othermagnetic circuit which includes the gap and the fixed keeper 153.

The coils 135, 137 are connected in electrical series and pulsed by a DCcurrent, in response to an abnormal or overload condition in any of thethree pole units of the circuit breaker, by means of an overcurrentprotective device of the type specifically described in the patentapplication of John David Watson et al., Ser. No. 765,584, tiled Oct. 7,1968. The polarity of the coils 135, 137 is such that when the coils arepulsed the eurent in the coils bucks the magnetic flux in the magneticcircuit that includes the movable keeper to raise the reluctance of themagnetic circuit that includes the movable keeper 165 whereupon magneticflux transfers to the magnetic circuit that includes the xed keeper 153.Thus, when the coils 135, 137 are pulsed the movable keeper 165 isreleased and the charged kickout spring 179 moves the actuating rod 161to the left to operate through the shock-absorbing spring 171 to movethe movable keeper 165 from the set position seen in FIG. 6 to thetripping position seen in FIG. 7. Upon movement of the movable keeper165 and actuating rod 161 from the set position to the tripping positionseen in FIG. 7, the actuating rod 161 pivots the trip member 187counterclockwise to the tripping position seen in FIGS. 7 and 4. As canbe understood with reference to FIGS. 7, 4 and .1, when the trip member187 moves to the tripping position the part 195 of the trip member 187engages the part 77, that is connected to the latch 63 (FIG. 1) to pivotthe latch 63 in a counterclockwise (FIG. l) direction about the pivot65. This unlatching movement of the latch 63 (FIG. 1) serves to releasethe latch 53 to effect an opening operation of the circuit breaker inthe same manner as was hereinbefore described.

The parts are shown in FIGS. 4 and 7 at the instant when the trip member187 is moved to the tripping position With the tie bar 19 still shown inthe closed position about to be operated to the open position as thelatches are released. When the circuit breaker is operated to the openposition the rod 19 moves from the position seen in FIGS. 4 and 7 (seenin broken lines in FIG. 6) to the open position seen in FIGS. 5 and 6.As the tie bar 19 moves to the open position seen in FIGS. 5 and 6, thetie bar engages the resilient leaf spring 199 of the resilient resetmember 191 to pivot the reset member 191 in a counterclockwise directionabout the pivot 193. During this movement, the projecting portion 203 ofthe reset member 191 engages the trip member 187 to pivot the tripmember 187 in a clockwise direction about the pivot 189l moving theactuating rod 161 from the released or tripping position seen in FIG. 7back to the set or reset position seen in FIG. 6. As the actuating rod161 moves to the position seen in FIG. 6, the rod 161 operates throughthe washer 167 to pull the movable keeper 165 back into the set positionin engagement with the pole pieces 131, 133.

The coils 135, 137, which were only momentarily pulsed l to effect thetripping operation, are not energized when the circuit breaker istripped and they will not be energized when the circuit breaker isreclosed unless there is a condition in one of the pole units that wouldoperate the protective relay to again energize the coils 135, 137. Thus,when the movable keeper 165 is re-engaged in the set position engagingthe pole pieces 131, 133 the magnetic flux will automatically transferfrom the higher reluctance magnetic circuit that includes the fixedkeeper 153 back through the lower reluctance magnetic circuit thatincludes the movable keeper 165 so that the magnetic flux in the circuitthrough the movable keeper 165 will again work to hold the movablekeeper 165 in the set position seen in FIG. 6 until the coils 135, 137are again pulsed.

As can be understood with reference to the drawings, with the rigid tiebar 19 operating against a resilient leafspring member 199 themanufacturing tolerances and positioning of parts in the breaker is lesscritical in that when the tie bar 19 moves past the point where themovable keeper 165 engages the pole pieces the tie bar 19 will merelyflex the leaf-spring 199 without applying damaging forces to the partsof the trip device.

Following an opening operation of the circuit breaker, the circuitbreaker is manually closed by operation of the handle operatingstructure 113 (FIG. 1) in the same manner as was hereinbefore described.During the closing operation, the tie bar 19 moves from the full lineposition seen in FIG. 6 to the broken line position seen in FIG. 6 (fromthe position seen in FIG. 5 to the position seen in FIG. 3) whereuponthe spring 201 biases the reset member 191 clockwise about the pivot 193from the position seen in FIG. 6 to the position seen in FIG. 3.

With the trip device in the reset position, if the actuating rod 161 ismoved slightly to the left under shock conditions, some of the shockforce will be absorbed by the shock-absorbing spring 171 Without beingdirectly applied to the movable keeper 165. The actuating rod 161extends through an opening, in the movable keeper 165, that is largeenough to permit relative movement of the rod to the left (FIG. 6)without moving the movable keeper 165. The spring 171, however, must besufliciently stiff so that when the movable keeper 16S is released themovable keeper will be immediately biased to the left under the biasingforce of the spring 179 operating through the rod 161 and spring 171.

I claim:

1. A circuit breaker comprising a stationary contact, a movable contactcooperable with said stationary contact, an operating mechanismreleasable to effect automatic opening of said contacts, trip meanscomprising a rnagnetic device, said magnetic device comprising magneticpole-piece means, a magnetic fixed keeper supported at a first end ofsaid pole-piece means, a magnetic movable keeper at a second end of saidpole-piece means opposite said first end, an elongated actuatoroperatively connected at one end thereof to said movable keeper andextending at the other end thereof past said fixed keeper, permanentmagnet flux supplying means positioned between said fixed keeper andmovable keeper and providing magnetic flux that operates in a firstmagnetic circuit through said pole-piece means and said movable keeperto maintain said movable keeper and said actuator in a set position inwhich set position said movable keeper is positioned against saidpole-piece means, biasing means biasing said actuator and movable keeperaway from said pole-piece means, means for effecting a transfer ofmagnetic flux from said first magnetic circuit to a secondmagneticcircuit which is through said pole-piece means and said fixedkeeper whereupon said movable keeper is released, upon release of saidmovable keeper said biasing means biasing said movable keeper and saidactuator away from said pole-piece means to bias said movable keeper andsaid actuator to a tripping position in which tripping position saidmovable keeper is spaced from said pole-piece means, upon movement ofsaid movable keeper and said actuator to said tripping position saidactuator at said other end thereof operating to effect release of saidoperating mechanism to thereby effect opening of said contacts, andmeans automatically moving said actuator and Said movable keeper back tosaid set position upon opening of said contacts.

2. A circuit breaker according to claim 1, said magnetic device beingconstructed and arranged such that the magnetic reluctance in saidsecond magnetic circuit is higher than the magnetic reluctance in saidfirst magnetic circuit, said means for transferring magnetic flux fromsaid first magnetic circuit to said second magnetic circuit comprisingcoil means energized upon the occurrence of overload current conditionsto effect said transfer of magnetic flux, and upon movement of saidmovable keeper and said actuator back to said set position with saidcoil means deenergized magnetic flux automatically transferring fromsaid second magnetic circuit to said first magnetic circuit tO work tomaintain said movable keeper and said actuator in said set position.

3. A circuit breaker according to claim 2, said means for moving saidmovable keeper and said actuator back to said set position comprisingresilient reset means operatively connected to said actuator, saidoperating mechanism comprising a movable member movable to an openposition upon opening of said contacts and to a closed position uponclosing of said contacts, and upon movement of said movable member tothe open position said movable member engaging said resilient resetmeans and operating said resilient reset means to operate said actuatorand said movable keeper back to said set position.

4. A circuit breaker according to claim 3, said circuit breakercomprising a multi-pole circuit breaker, a stationary contact and amovable contact for each pole unit, a separate movable contact armcarrying each of said movable contacts, a rigid tie bar common to all ofsaid pole units and operatively connectedV to simultaneously move al1 ofsaid movable contact arms, and said movable member that engages saidresilient reset means being Said tie bar.

5. A circuit breaker according to claim 3, said operating mechanismcomprising latch means movable to a releasing position to release saidoperating mechanism, said trip device comprising a trip memberoperatively connected to said actuator and movable upon movement of saidmovable keeper and said actuator to the tripping position to engage saidlatch means and to move said latch means to the releasing position, andsaid resilient reset means comprising a reset member separate from saidtrip member and supported to actuate said trip member said movablekeeper and said actuator back to the set position upon opening of saidcontacts.

6. A circuit breaker according to claim 5, said trip means comprising atrip housing structure, said magnetic device being supported within saidtrip housing structure, said trip housing structure having opening meanstherein, said actuator extending out through said opening means, andsaid trip member and said resilient reset means being supported on saidtrip housing structure external of said trip housing structure.

7. A circuit breaker according to claim 4, means supporting said tripmember on a first fixed pivot, means supporting said resilient resetmeans on a second fixed pivot separate from said first fixed pivot,means connecting said trip member with said actuator, spring meansbiasing said resilient reset means toward an initial position, uponrelease of said movable keeper said movable keeper said actuator andsaid trip member operatively moving to release said latch means withsaid resilient reset means remaining in said initial position, uponopening of said contacts said movable member engaging said resilientreset means and moving said resilient reset means to the set positionduring which movement said resilient reset means operates to move saidmovable keeper said trip member and said actuator back to the setposition, and upon the occurrence of a subsequent closing operation saidspring means biasing said resilient reset means back to said initialposition during which movement of said resilient reset means saidmovable keeper said trip member and said actuator remain in said setposition.

8. A circuit breaker according to claim 3, said magnetic device havingopening means therein, said actuator comprising an elongated actuatingrod operatively connected to said movable keeper at one end thereof andextending through said opening means past said fixed keeper, a tripmember operatively connected to said other end of said actuating rod andmovable upon movement of said actuating rod to effect release of saidoperating mechanism, and said resilient reset means being supported inproximity to said other end of said actuating rod and being operable tosaid reset position to move said actuating rod said movable keeper andsaid trip member back to the set position.

9. A circuit breaker according to claim 8, a first spring means biasingsaid actuating rod toward the tripping position, said movable keeperhaving an opening therein, said actuating rod at said one end thereofextending through said opening and being connected to said movablekeeper to move said movable keeper with said actuating rod back to saidset position, and a shock-absorbing spring connected between saidactuating rod and said movable keeper to permit said actuating rod tomove toward the tripping position under shock conditions with saidmovable keeper in the set position during which movement said actuatingrod compresses said shock-absorbing spring and moves relative to saidset movable keeper, upon release of said movable keeper said trippingspring operating said actuating rod to operate through saidshockabsorbing spring to move said movable keeper and said actuating rodto the tripping position.

References Cited UNITED STATES PATENTS 2,278,971 4/1942 Boehne 335--1792,840,663 6/1958 Horn 335-174 3,070,730 12/1962 Gray 335-256 3,072,765l/l963 Hauser 335--174 3,202,886 8/1965 Kramer 335-254 BERNARD A.GILHEANY, Primary Examiner H. BROOME, Assistant Examiner

